The present invention is based on a yaw-rate sensor according to the definition of the species in the independent patent claim.
Yaw-rate sensors in which a first and a second Coriolis element are arranged on the surface of a substrate are already known from the U.S. Pat. No. 5,728,936. The Coriolis elements are induced to oscillate in a first axis. The deflections of the Coriolis elements due to a Coriolis force in a second axis, which is likewise parallel to the substrate, are verified.
In contrast, the yaw-rate sensor of the present invention having the features of the independent patent claim has the advantage that a clear frequency separation of the different oscillation modes is achieved. Thus, it is possible to specifically excite the antiphase oscillation by the selection of an appropriate excitation frequency.
Further advantages and improvements are yielded by the measures in the dependent patent claims. If the gravitational centers of the Coriolis elements move perpendicular to a straight connecting line between the gravitational centers, then on average over time, the deflections of the Coriolis elements because of the Coriolis force lie on one and the same axis, in which an angular acceleration exerts no force component whatsoever. A further form of the excitation is effected by an oscillation of both Coriolis elements on one axis.
The Coriolis elements are induced to oscillate particularly easily by a drive element which transmits driving forces through springs. In this case, the Coriolis element may be suspended completely on this drive element. Electrostatic comb drives may be provided on the drive elements as excitation means. The Coriolis force may be verified in that the Coriolis element has movable electrodes which are arranged opposite stationary electrodes. However, verification elements may also be provided to which the Coriolis forces are transmitted by springs. In this case, it is possible in particular to suspend the verification elements in such a way on the substrate that only a movement in the direction of the Coriolis forces takes place. Interference effects because of a movement of the movable electrodes which are not in the verification direction are thereby suppressed.